WO2024252223A1

WO2024252223A1 - Comb assembly and haircare appliance

Info

Publication number: WO2024252223A1
Application number: PCT/IB2024/055169
Authority: WO
Inventors: Ross GEDDES; Jacob Alexander
Original assignee: Dyson Technology Ltd
Current assignee: Dyson Technology Ltd
Priority date: 2023-06-06
Filing date: 2024-05-28
Publication date: 2024-12-12
Anticipated expiration: 2025-12-06
Also published as: GB202308406D0; GB2630758A

Abstract

A comb assembly is described. The comb assembly comprises a tooth structure to receive hair within a passage through the tooth structure, and an actuator system operable to cause the tooth structure to expand the passage and to constrict the passage. The comb assembly further comprises a sensor arrangement including a sensor to sense, when hair is held in the passage, a load on the tooth structure indicative of a tensile load exerted by the tooth structure on the hair held in the passage by the tooth structure, and output a sensor signal indicative of the sensed load on the tooth structure.

Description

COMB ASSEMBLY AND HAIRCARE APPLIANCE

BACKGROUND

Various haircare appliances are known that generate a flow of air for discharge onto a user’s hair. One example is a hair dryer or hair styler, which supplies a heated flow of air for styling and/or drying a user’s hair. Basic use of a hair dryer for drying a user’s hair involves holding the hair dryer at a distance from the user’s hair while directing discharged hot air onto the user’ s hair.

Attachments for haircare appliances (such as hair dryers or hair stylers) are known which provide the appliance with additional functionality. For example, when fitted to a haircare appliance, such attachments may facilitate application of a particular style to a user’s hair and/or may increase the suitability of the haircare appliance for use with a particular hair type.

One type of attachment for a haircare appliance (such as a hair dryer) is a comb attachment. Typically, comb attachments include a comb having a row of spaced teeth. In use, a user’s hair is received between the teeth of the comb and the comb is moved along the hair to style the hair. In some cases, a comb attachment can be used in this way to smooth and straighten a user’s hair (for example to smooth straight hair, or to smooth/straighten curly and/or coily hair). Such smoothing and straightening is at least partly provided by the teeth of the comb pulling (i.e. applying tension to) a user’s hair as the teeth are moved along the user’s hair.

SUMMARY

Comb attachments for haircare appliance may be difficult for some users. In particular, users may struggle to achieve the desired tension in the hair and, thus, may struggle achieving the desired hairstyle. Moreover, such issues are more generally applicable also to other comb types, such as traditional combs not attached to a haircare appliance. According to a first aspect, there is provided a comb assembly including: a tooth structure arranged to receive hair within a passage through the tooth structure; an actuator system operable to cause the tooth structure to expand the passage and to constrict the passage; a sensor arrangement including a sensor configured to sense, when hair is held in the passage by the tooth structure, a load on the tooth structure indicative of a tensile load exerted by the tooth structure on the hair held in the passage by the tooth structure, and output a sensor signal indicative of the sensed load on the tooth structure.

The comb assembly may include a control module. The control module may be configured to control the actuator system in response to the sensor signal to cause the tooth structure to expand the passage if the sensed load is greater than an upper threshold.

In use, the tooth structure of the comb assembly may grip hair by constricting the passage. By configuring the control module to expand the passage if the sensed load is greater than the upper threshold, the grip onto the hair may be reduced to thereby reduce the tensile load on the hair. Thus, an excessive tensile load on the hair may be prevented.

The control module may control the actuator system to cause the tooth structure to constrict the passage if the sensed load is less than a lower threshold.

By configuring the control module to constrict the passage if the sensed load is less than the lower threshold, the grip onto the hair may be increased to thereby increase the tensile load on the hair. Thus, a minimum tensile load on the hair may be provided. The minimum tensile load may ensure that hair is less prone to disengage the comb assembly, for example by being blown out of the comb assembly where the comb assembly is attached to a hairdryer or integrated with a hairdryer.

The upper threshold and the lower threshold may be different, defining a target tension range. The upper threshold and the lower threshold may coincide, defining a target tension. By controlling the actuator system to expand and constrict the passage dependent on the sensed load, the tensile load exerted by the tooth structure may in use tend towards the target tension or the target tension range.

The control module may include a closed-loop controller configured to control the actuator system based on the sensor signal to towards a target tension. For example, the closed-loop controller may be a PID controller (“proportional-integral-derivative” controller), P controller, a PI controller, or a PD controller.

The sensor arrangement may include a plurality of sensors configured to sense the load on the tooth structure.

By including the plurality of sensors, sensor coverage and sensing accuracy of the sensor arrangement may be improved, and signal noise may be reduced. For example, sensors may be arranged in pairs as a Wheatstone bridge for temperature compensation and improved accuracy. Also, utilising a plurality of sensors may be desirable for sensing particular load distributions or stress concentrations that may be difficult to sense accurately for a single sensor, such as a non-uniform load on the tooth structure at a location remote from the single sensor.

The tooth structure may be divided into a plurality of portions, each portion forming a passage. The sensor arrangement may include a plurality of sensors. Each sensor may be configured to sense a load on a corresponding portion of the tooth structure. The sensor arrangement may be configured to output a sensor signal indicative of the sensed loads of the plurality of sensors. The control module may be configured to control the actuator system to cause the tooth structure to expand the passages if the sensed load sensed by any sensor is greater than the upper threshold.

By dividing the tooth structure into a plurality of portions and providing each portion with a sensor, the sensing accuracy may be improved and sensing refined for detecting non- uniform load on the tooth structure. The actuator system may include a plurality of actuators. Each portion of the tooth structure may be actuatable by a corresponding actuator of the actuator system to expand and constrict a corresponding passage or passages.

The upper threshold may have an adjustable value. The control module may be operable to adjust the value of the upper threshold.

The lower threshold may have an adjustable value. The control module may be operable to adjust the value of the lower threshold.

Adjustment of the upper/lower threshold may be desirable, for example dependent on a hair type, desired hair style or hair condition.

The comb assembly may be configured to communicate with an external user device and may be configured to receive from the external user device a command instructing the control module to adjust the upper threshold, and may be configured to receive from the external user device a command instructing the control module to adjust the lower threshold.

Utilising an external user device to adjust the upper threshold may be particularly convenient.

The command instructing the control module to adjust the upper threshold or lower threshold may be based on a user profile. The user profile may include information relating to at least one of user hair type, hair condition, hair length and desired hair style.

Utilising user information provided to the user device may be particularly convenient for adjusting the threshold value by taking into account hair type, desired hair style or hair condition.

The tooth structure may include a first row of teeth and a second row of teeth. The passage may be formed between the first row of teeth and the second row of teeth. The actuator system may be operable to cause relative motion, e.g. relative displacement of the first row of teeth and the second row of teeth, or relative rotation of teeth to expand the passage and to constrict the passage. The control module may be configured to control the actuator system in response to the sensor signal to cause relative motion of the first row of teeth and the second row of teeth to expand the passage if the sensed load is greater than the upper threshold.

The comb assembly may be configured to output a user notification based on the sensor signal, e.g. if the sensed load approaches the upper threshold. The user notification may include at least one of visual notification, audible notification or haptic notification.

By notifying the user based on the sensor signal, e.g. about approaching or exceeding the upper threshold, the comb assembly may urge the user to cautiously work the hair using the comb assembly. This may in use prevent damage to the hair, or injury to the user, for example where a knot is encountered by the comb assembly and the user may desire to proceed with cautious application of force.

The control module may be configured to transmit a command to an external user device to cause the external user device to output a user notification based on the sensor signal, e.g. if the sensed structural load approaches the upper threshold.

The control module may be configured to exclusively cause the external user device to output the user notification, i.e. without the comb assembly otherwise outputting a user notification.

The control module may be configured to transmit the sensor signal to the external user device to output the sensor signal, for example displaying the sensor signal to the user following optional processing of the sensor signal.

The actuator system may be operable to cause the tooth structure to expand the passage to a maximally expanded configuration. The control module may be configured to control the actuator system to cause a vibration of the tooth structure if the passage is in the maximally expanded configuration and the sensed load is more than the upper threshold.

Where the tooth structure is in a maximally expanded configuration and the sensed load exceeds the upper threshold, the comb assembly is unable to further expand the passage in order to reduce the structural load. As such, user intervention may be necessary and the comb structure may indicate this to the user, e.g. by causing reciprocating motion of the tooth structure, to carefully work the comb assembly through the user’s hair. Moreover, such a situation may be caused by the presence of a knot in the user’s hair, and the reciprocating motion of the tooth structure may assist the user with disentangling of the knot.

Where the comb assembly includes the first row of teeth and the second row of teeth, the vibration of the tooth structure may be caused by reciprocating displacement of the rows of teeth relative to each other.

The sensor arrangement may include at least one strain gauge sensor configured to sense the load on the tooth structure, for example a micro strain gauge.

The comb assembly may further comprise a resilient member coupling the tooth structure and the actuator system. The actuator system may be configured to displace the resilient member in order to cause relative displacement of the tooth structure.

By coupling the tooth structure and the actuator system via the resilient member, this may in use provide for smoother operation. This coupling via the resilient member may be particularly desirable in combination with the vibration of the tooth structure.

According to a second aspect, there is provided a haircare appliance including a comb assembly as described above. The haircare appliance may be configured to supply a heated airflow through the comb assembly.

The comb assembly may be detachable from a main body of the haircare appliance. According to a third aspect, there is provided a haircare system including the haircare appliance as described above, and further comprising an external user device. The external user device may be configured to send to the haircare appliance a command instructing the hair styling appliance to adjust the upper threshold.

According to a fourth aspect, there is provided a computer-readable medium storing instructions to adjust the upper threshold value. The computer-readable medium may store instructions to adjust the lower threshold value.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure l is a perspective view of a comb assembly.

Figure 2 is a schematic side view of the comb assembly in a first configuration.

Figure 3 is a schematic top view of the comb assembly in the first configuration.

Figure 4 is a schematic side view of the comb assembly in a second configuration.

Figure 5 is a schematic top view of the comb assembly in the second configuration.

Figure 6 is a schematic cross-sectional view of the comb assembly in the first configuration.

Figure 7 is a graph illustrating tensile load on hair with tension control disabled.

Figure 8 is a graph illustrating tensile load on hair with tension control enabled.

Figure 9 is a schematic view of a haircare system comprising a haircare appliance including the comb assembly, and comprising an external user device.

DETAILED DESCRIPTION

Figure 1 is a perspective view of a comb assembly 10. The comb assembly 10 is for mounting to a haircare appliance, such as a hairdryer (not shown) supplying an airflow through the comb assembly 100. The following description of the comb assembly 10 is applicable also to other examples, such as the comb assembly 10 integrated with the hairdryer, or the comb assembly 10 provided as a traditional comb which may not be for attachment to a hairdryer. The comb assembly 10 includes a tooth structure 100. In use, a user’s hair is received into the tooth structure 100 and the comb assembly 10 is used to work the hair. Suitably the comb assembly 10 forms a plurality of passages 110 and is arranged to receive hair within the passages 110 through the tooth structure 100.

The comb assembly 10 includes an actuator system 200. The actuator system 200 is operable to cause the tooth structure 100 to expand the passages 110 and to constrict the passages 110. By constricting the passages 110, grip on the user’s hair by the tooth structure 100 is increased. By expanding the passages 110, grip on the user’s hair is relaxed. The actuator system 200 may include any suitable motor configuration, e.g. a servo motor, a linear actuator. The actuator system 200 may include any suitable mechanism for actuation, such as a rack and pinion mechanism or a scotch yoke mechanism.

The comb assembly 10 includes a sensor arrangement 300. The sensor arrangement 300 includes a plurality of sensors 310, 320 configured to sense a load (or ‘structural load’) on the tooth structure 110. When hair is held in the passages 110 of the tooth structure 100, with the passages 110 suitably constricted, moving the comb assembly 10 along the hair causes a tensile load on the hair and a corresponding load on the tooth structure 100. The sensors 310, 320 are configured to sense the load on the tooth structure 100, which is indicative of the tensile load on the hair. The sensor arrangement 300 is configured to output a sensor signal indicative of the sensed load on the tooth structure.

The comb assembly 10 includes a control module 400 (or ‘controller’). The control module 400 receives the sensor signal and is configured to control the actuator system 200 based on the sensor signal. In particular, the control module 400 is configured to control the actuator system 200 to cause the tooth structure 100 to expand the passages 110 if the sensed load is greater than an upper threshold.

By actuating the tooth structure 100 to expand the passages 110, grip on the user’s hair is relaxed. As such, an excessive tensile load on the user’s hair may in use be reduced. It is noted that an excessive tensile load may cause discomfort for the user, or hair damage, or even physical injury. For example, traction alopecia may be caused. Since the comb assembly 10 is configured to expand the passages 110 if the sensed load is greater than the upper threshold, the comb assembly 10 may improve user comfort and reduce the risk of damage to hair or injury to the user. Thus, the comb assembly 10 may provide for automatic tension control.

In use, automatic tension control may be triggered manually by the user, for example by depressing a button on the comb assembly 10, or for example by a suitable sensor (not shown) detecting hair in the passages 110.

The control module 400 is further configured to control the actuator system 200 to cause the tooth structure 100 to constrict the passages 110 if the sensed load is less than a lower threshold. The lower load may ensure that hair is less prone to disengage the comb assembly, for example by being blown out of the comb assembly where the comb assembly is attached to a hairdryer or integrated with a hairdryer.

By causing the passages 110 to expand and to constrict in response to the sensed load, the comb assembly 10 may drive the tensile load on the user’s hair towards a target tension value, or towards a target tension range. The target tension range may be, for example, 0.2 to 4 Newtons on hair in one of the passages 110. In some examples, the target tension range may be 0.5 to 3 Newtons. Similarly, the target tension value may be any value in the range of 0.2 Newtons to 4 Newtons, or in the range of 0.5 to 3 Newtons, for hair in one of the passages 110.

In some examples, the upper threshold and the lower threshold coincide, thereby providing a target tension value. In some examples, the control module 400 may be configured to drive the tensile load towards the target tension value and additionally determine whether the load is greater than or smaller than the target tension range.

In use, the control module 400 is configured to utilise closed-loop control for controlling the actuator system 200. Suitably, the control module 400 includes a PID controller (proportional-integral-derivative controller) for determining the actuation and controlling the actuator system 200 to maintain the target tension in the user’s hair when using the comb assembly 10.

Figures 2 to 5 are schematic illustrations of the comb assembly 10. Figure 2 is a side view and Figure 3 is a plan view of the comb assembly 10 with the passages 110 shown in an expanded configuration. Figures 4 and 5 are corresponding views, but with the passages 110 shown in a constricted configuration.

The tooth structure 100 includes a first row of teeth 120 and a second row of teeth 130 with the passages 110 formed therebetween. The actuator system 200 is operable to cause relative displacement of the first row of teeth 120 and the second row of teeth 130 to expand and constrict the passages 110. In the example shown in Figures 2 to 5, the second row of teeth 130 is displaceable by the actuator system 200 while the first row of teeth 120 remains stationary.

In Figures 2 and 3, the tooth structure 100 is in the expanded configuration wherein the second row of teeth 130 is generally aligned with the first row of teeth 120, with the passages 110 in a maximally expanded configuration. By contrast, in Figures 4 and 5 the tooth structure 100 is in the constricted configuration wherein the second row of teeth 130 is displaced relative to the first row of teeth 120. As such, the passages 110 are changed from a linear configuration shown in Figures 2 and 3 to a non-linear configuration shown in Figures 4 and 5. When a hair tress 20 is received into the passages 110 in the linear configuration, the hair tress 20 may extend through the passages 110 generally linearly. When the passages 110 are brought into the non-linear configuration, the hair tress 20 is urged to extend through the passages 110 generally non-linearly. Thus, a path length through the tooth structure 100 is increased for the hair tress 20 when the tooth structure 100 is brought from the expanded configuration to the constricted configuration, causing grip onto the hair tress 20 by the tooth structure 100 to increase.

The tooth structure 100 includes a shell 140 (or ‘housing’) from which the rows of teeth 120, 130 extend. In this example, the first row of teeth 120 is formed integrally with the shell 140. The sensors 310, 320 of the sensor arrangement 300 are provided on the shell 140 and configured to sense the load on the tooth structure 100 when in use exerting a tensile load on the user’s hair. In some examples, at least one sensor or all sensors may be located on an inner body 150, e.g. to which the second row of teeth 120 is connected, or an inner shell (not shown).

In the present example, the sensors 310, 320 are micro strain gauge sensors configured to sense a deformation of the tooth structure 100, and in particular the shell 140, caused by the load that in use acts on the tooth structure 100.

The tooth structure 100 is divided into a plurality of portions 102, 104 wherein each portion forms at least one passage 110. In this example, the tooth structure 100 is divided into a first portion 102 and a second portion 104 at a split line 105. The first portion 102 includes a first part of the first row of teeth 120 and a first part of the shell 140, and similarly the second portion 104 includes a second part of the first row of teeth 120 and a second part of the shell 140.

The sensors 310, 320 of the sensor arrangement 300 are distributed across the portions 102, 104 of the tooth structure 100 to sense the load on each portion 102, 104. That is to say, the first sensor 310 is provided on the first portion 102 of the tooth structure 100, and the second sensor 320 is provided on the second portion 104 of the tooth structure 100. The sensor arrangement 300 is configured to output a sensor signal indicative of the sensed loads of the sensors 310, 320, and the control module 400 is configured to control the actuator system 200 to cause the tooth structure 100 to expand the passages 110 if the sensed load sensed by any sensor 310, 320 is greater than the upper threshold, and similarly to constrict the passages 110 if the sensed load sensed by any sensor 310, 320 is smaller than the lower threshold. In this example, the actuator system 200 includes a single actuator which acts on the entire second row of teeth 130. More generally, multiple actuators may be provided to act on separate portions of the second row of teeth 130, for example in response to a sensor signal from a corresponding sensor 310, 320.

Figure 6 is a sectional view of the comb assembly 10 illustrating how the second row of teeth 130 and the actuator system 200 are coupled in this example. The comb assembly 10 includes a resilient member connecting the second row of teeth 130 and the actuator system 200. The actuator system 200 is configured to displace the resilient member 210 in order to cause relative displacement of the tooth structure 100 by displacing the second row of teeth 130. By coupling the tooth structure 100 and the actuator system 200 via the resilient member 210, smoother operation may be achieved.

In this example, the second row of teeth 130 is coupled to the inner body 150, and the inner body 150 is coupled to the resilient member 210. In some examples, the resilient member 210 couples the second row of teeth 130 directly to the actuator system 200. In other examples the resilient member 210 couples the second row of teeth 130 indirectly to the actuator system 200.

The resilient member 210 may be made of any suitable material or configuration. For example, the resilient member 210 may be provided, for example, as a rubber body or a spring or an elastic plastic body.

Figures 7 and 8 are graphs illustrating tensile load on hair when using the comb assembly 10 over a period of time. For both of Figures 7 and 8, the comb assembly 10 has been configured to grip hair by constricting the passages 110, but for the example of Figure 8 tension control is carried out also against the upper threshold. That is to say, for the example of Figure 7 tension control does not include expanding the passages 110 when the sensed load exceeds the threshold value.

A straight horizontal line 771 indicates the target tension in Figures 7 and 8. As can be seen in Figure 7, the tensile load greatly exceeds the target tension once the comb assembly 10 engages the user’s hair. By contrast, in Figure 8 the comb assembly 10 drives the tooth structure 100 such that the target tension is more closely maintained for the duration over which the comb assembly 10 engages the user’s hair and, in particular, comparatively long periods of excessive tensile load are avoided. Where a hair knot is encountered by the comb assembly 10, expanding of the passages 110 may not reduce the sensed load, e.g. because entangled hair could be spread across multiple passages 110. As such, the sensed load may in use approach or exceed the upper threshold although the passages 110 are in a maximally expanded configuration. In such circumstances, i.e. approaching/exceeding the upper threshold despite being in the maximally expanded configuration, the control module 400 is configured to operate in a knot teasing mode. In the knot teasing mode, the control module 400 controls the actuator system 200 to vibrate the tooth structure 100. Vibration of the tooth structure 100 may be achieved, for example, by repeatedly constricting and expanding the passages 110, or by using a separate vibration module (not shown).

The knot teasing mode may enable the user to avoid having to work their way up the length of hair in order to tease out knots since the comb assembly 10 may assist the user with teasing out knots and ensuring comfort.

Figure 9 illustrates a haircare system 1000 comprising a haircare appliance 30 which includes the comb assembly 10, and an external user device 40. The haircare appliance 30 may be any haircare appliance, e.g. a hairdryer.

As shown in Figure 9, the comb assembly 10 is provided as an attachment to a main body 32 of the haircare appliance 30. In the example described with reference to Figure 9, the entire comb assembly 10 is detachable from the main body 32. In some examples, the comb assembly 10 may in part be integrated with the main body 32 and in part be separable from the main body 32. For example, the control module 400 may be integrated with the main body 32 while the sensor arrangement 300 and the actuator system 200 may be provided on a detachable part of the comb assembly 100.

In some examples, the comb assembly 10 is powered by the main body 32 of the haircare appliance 30, e.g. by means of a wired connection or inductive coupling. In some examples, the comb assembly 10 includes a power source, e.g. a battery. The user device 40 may be any user device for communicating with the haircare appliance 30 and the user, such as a mobile phone or a tablet. The haircare appliance 30 is configured to communicate with the user device 40, e.g. through a wired or wireless connection, such as Bluetooth or Wi-Fi. Suitably, the haircare appliance 30 comprises a communication module 34 for communicating with the user device 40.

The target tension value and the target tension range are adjustable. For example, the target tension may be adjustable locally, i.e. directly via the haircare appliance 30 using a suitable input such as a dial, or remotely via the user device 40. In this example, the haircare appliance 30 is configured to receive from the user device 40 a command instructing the haircare appliance 30 to adjust the threshold values to thereby adjust the target tension range. In some examples, the command instructing adjustment of the threshold values is based on a user profile stored by the user device 40 or an external server (not shown). The user profile may include information relating to at least one of user hair type, hair condition, hair length and desired hair style. As such, the threshold values may be adjusted without the user needing to specify an adjustment. In some examples, the command instructing adjustment of the threshold values is issued by the user directly specifying an adjustment of the threshold values.

Utilising user information provided to the user device may be particularly convenient for adjusting the threshold values by taking into account hair type, desired hair style or hair condition.

The haircare system 100 is configured to output a user notification based on the sensed load to provide user feedback. Such user notifications may include at least one of visual notifications, audible notifications, or haptic notifications. User notifications may be output by the comb assembly 10, the haircare appliance 30, the user device 40, and any combination thereof.

The haircare system 100 according to Figure 9 is configured to, in response to the sensor signal, control the actuator system and to output the user notification. In some examples, the haircare system 100, or the comb assembly 10, is configured to control the actuator system in response to the sensor signal without outputting user notifications. In some examples, the haircare system 100, or the comb assembly 10, is configured to output the user notification without controlling the actuator system in response to the sensor signal.

The haircare appliance 30 is configured to output a user notification based on the sensed load. In particular, the haircare appliance 30 is configured to output the user notification in response to the sensed load approaching the upper threshold. Suitably, the haircare appliance 30 includes a notification module 36. The notification module 36 may be configured to output a visual notification, an audible notification or a haptic notification, e.g. a vibration. In this example, the notification module 36 is provided as a loudspeaker configured to output an audible notification to the user in order to alert the user about approaching or exceeding the upper threshold. In some examples, an audible notification is output using the actuator system 200, e.g. by driving a motor of the actuator system 200 at a frequency causing the motor to generate an audible noise, such as a whining noise.

User notifications may be output via the user device 40. According to such examples, the haircare appliance 30 communicates with the user device 40 using the communication module 34. User notifications output via the user device 40 may be, e.g., visual or audible notifications, or both visual and audible notification. For example, a message may be displayed by the user device 40 and a sound may be output by the user device 40 to alert the user. In some examples, the user is informed that the threshold value has been exceeded. In some examples, the user is instructed to reduce pull on the hair by means of the comb assembly 10.

In some examples, a user notification is output when the comb assembly 10 is operated in the knot teasing mode. That is to say, the user notification may inform the user that the haircare appliance 30 is operating in a particular operational mode associated with teasing out knots, thereby alerting the user to carefully work the hair with the haircare appliance 10. In some examples, the knot teasing mode may include using the actuator system 200 to generate an audible noise indicative of operation in the knot teasing mode.

Claims

1. A comb assembly including: a tooth structure arranged to receive hair within a passage through the tooth structure; an actuator system operable to cause the tooth structure to expand the passage and to constrict the passage; a sensor arrangement including a sensor configured to sense, when hair is held in the passage by the tooth structure, a load on the tooth structure indicative of a tensile load exerted by the tooth structure on the hair held in the passage by the tooth structure, and output a sensor signal indicative of the sensed load on the tooth structure.

2. The comb assembly according to claim 1, further comprising: a control module configured to control the actuator system in response to the sensor signal to cause the tooth structure to expand the passage if the sensed load is greater than an upper threshold.

3. The comb assembly according to claim 2, wherein the control module is further configured to control the actuator system to cause the tooth structure to constrict the passage if the sensed load is less than a lower threshold.

4. The comb assembly according to any preceding claim, wherein the control module includes a PID controller configured to control the actuator system based on the sensor signal to towards a target tension range.

5. The comb assembly according to any preceding claim, wherein the sensor arrangement includes a plurality of sensors configured to sense the load on the tooth structure; wherein the tooth structure is divided into a plurality of portions, each portion forming a passage; wherein the sensor arrangement includes a plurality of sensors, each sensor configured to sense a load on a corresponding portion of the tooth structure, and wherein the sensor arrangement is configured to output a sensor signal indicative of the sensed loads of the plurality of sensors; wherein the control module is configured to control the actuator system to cause the tooth structure to expand the passages if the sensed load sensed by any sensor is greater than the upper threshold.

6. The comb assembly according to any one of claims 2 to 5, wherein the upper threshold has an adjustable value, and the control module is operable to adjust the value of the upper threshold.

7. The comb assembly according to claim 6, wherein the comb assembly is configured to communicate with an external user device and is configured to receive from the external user device a command instructing the control module to adjust the upper threshold; and wherein the command instructing the control module to adjust the upper threshold is based on a user profile, and the user profile includes information relating to at least one of user hair type, hair condition, hair length and desired hair style.

8. The comb assembly according to any one of claims 2 to 7, wherein the tooth structure includes a first row of teeth and a second row of teeth; the passage is formed between the first row of teeth and the second row of teeth; the actuator system is operable to cause relative displacement of the first row of teeth and the second row of teeth to expand the passage and to constrict the passage; and the control module configured to control the actuator system in response to the sensor signal to cause relative displacement of the first row of teeth and the second row of teeth to expand the passage if the sensed load is greater than the upper threshold.

9. The comb assembly according to any preceding claim, wherein the actuator system is operable to cause the tooth structure to expand the passage to a maximally expanded configuration; and the control module is configured to control the actuator system to cause a vibration of the tooth structure if the passage is in the maximally expanded configuration and the sensed load is more than the upper threshold.

10. The comb assembly according to any preceding claim, wherein the comb assembly is configured to output a user notification based on the sensor signal; and the user notification includes at least one of visual notification, audible notification or haptic notification.

11. The comb assembly according to claim 10, wherein the control module is configured to transmit a command to an external user device to cause the external user device to output a user notification based on the sensor signal.

12. The comb assembly according to any preceding claim, wherein the sensor arrangement includes at least one strain gauge sensor configured to sense the load on the tooth structure.

13. The comb assembly according to any preceding claim, further comprising a resilient member coupling the tooth structure and the actuator system; and wherein the actuator system is configured to displace the resilient member in order to cause relative displacement of the tooth structure.

14. A haircare appliance including a comb assembly according to any preceding claim, wherein the haircare appliance is configured to supply a heated airflow through the comb assembly.

15. The haircare appliance according to claim 14, wherein the comb assembly is detachable from a main body of the haircare appliance.